A statistical approach for assessment of bronchodilator responsiveness in pulmonary function testing

Abstract

Objective: Because published criteria for bronchodilator responsiveness are based on population variability and compare only the single best measures before and after intervention, we hypothesized that the variability of the FEV1 and FEV3 of each patient would better determine that patient's responsiveness.

Design and interventions: Five 3-s forced expiratory maneuvers were used for each of 3 sequential portions of the study: baseline, after nebulized saline solution, and after nebulized albuterol.

Setting: Clinical pulmonary function laboratory in a county/university teaching hospital.

Patients: Fifty consecutive adult patients with obstruction referred for routine testing and thought to be able to complete the study. (The primary diagnoses were found to be equally divided between asthma, bronchitis, and emphysema; equal numbers had very severe, severe, moderate, mild, or minimal obstruction.)

Measurements and results: The primary finding was that 36 patients were found to be responders (consistent and statistically significant FEV1 and FEV3 improvement after albuterol). The 14 identified as nonresponders would have been so categorized by all other published criteria. For assessing responsiveness, we found FEV3 measures preferable to vital capacity measures, because the latter depends on the duration of the maneuver.

Conclusions: The percentage of responders identified is higher than recognized by any other published criteria. Most criteria would not have identified the responders with very severe or minimal airways obstruction.